Ektar should be fine as long as you carry a couple of correction filters like a UV and 81A for higher altitudes as I already suggested. Haze can
be quite beautiful with black and white film. If you study the Yosemite work of early masters like Muybridge and Watkins, you will see some
compositional strategies for light skies and wonderful atmospheric depth. Don't expect Ansel-Adamesque crisp light in the Valley in summer -
more likely up in the high country. But if you do want to cut thru haze, I'd pack a 25 red filter rather than a yellow or polarizer. A deep green
filter can also be nice when you want something less heavy than a red.